OK, I am not an expert here but this may be something to look at. ANT+ has different drivers that are installed on your PC when you first plug in the dongle.
The drivers installed use different hardware. The ANTUSB1 uses an SiLabs based driver and the ANTUSB-m and ANTUSB2 uses a LibUsb-Win32 based driver. It cold be that Zwift will only work with ANTUSB-m or ANTUSB2 while trainer road will work with the older driver. So how do you know which ANT dongle you have? The version of the USB stick is printed on the back of the plastic case. Otherwise the version can be determined by using the Device Manager.
Access the windows device manager by navigating to Control Panel > System > Device Manager. In the manager, ANTUSB2 sticks are called “ANT USB Stick 2”, under the “libusb-win32 devices” node. ANTUSB1 sticks are either called “ANT USB Device” or “ANT USB Stick”, under the “Universal Serial Bus Controllers” node.
To reinstall the drivers:
ANTUSB-m and ANTUSB2 drivers:
The ANTUSB-m and ANTUSB2 Stick drivers can be uninstalled via Windows’ Device Manager, then reinstalled by simply re-inserting the USB device and allowing windows update to download the drivers. Alternatively, the drivers could be downloaded from the website here and installed manually.
Re-installing the ANTUSB1 drivers is not always a trivial procedure. To do this properly, the old ANTUSB1 driver must first be completely removed from the system. Unfortunately, this is not as easy as uninstalling the driver via Device Manager. To completely remove the ANTUSB1 driver in Windows XP, please follow the technical note “Uninstalling USB1 Drivers” . Once the old drivers are completely removed, the new drivers may be installed using the standard procedure.